Human blood vessels damaged beyond repair by disease or injury are typically replaced with artificial blood vessels, commonly known as vascular grafts. Most grafts in use today are porous in nature, being typically formed of knitted or woven fibers. However, in order for the porous graft to conduct fluid without leaking, it must be impregnated with a material that ensures hemorrhage-free conduction of blood.
One proposed method for forming an artificial vascular graft is disclosed in U.S. Pat. No. 4,842,575. As taught therein, an aqueous slurry of collagen fibrils is deposited in the lumen of a previously prepared graft and manually massaged to ensure intimate mixing of the collagen into the porous structure of the graft substrate. After massaging, the collagen is dried and cross-linked by exposure to a formaldehyde vapor. This procedure is repeated as necessary to ensure a blood-tight graft. There are numerous drawbacks to grafts produced by this method. First, grafts produced by manual massaging will have an uneven distribution of collagen throughout the graft walls, resulting in uneven porosity. This requires repeated applications by manual massaging, typically six applications, according to the teachings of the patent. In addition, these grafts may have excess collagen deposited throughout the interior wall of the graft, yielding an uneven flow surface. This can result in excess collagen being carried away by the blood flow, and can cause postsurgical complications. Hence, this method lacks the ability to control the internal wall flow surface characteristics and does not provide consistent uniformity in each graft. Because this method is labor intensive, it is slow, inefficient, and unreliable.
Consequently, there is a need for a method of efficiently producing storable, surgically-ready, protein-impacted grafts that enables reliable control over the rate and direction of impaction.